Higgs boson mass, neutrino masses and mixing and keV dark matter in an U(1) R − lepton number model

Abstract

We discuss neutrino masses and mixing in the framework of a supersymmetric model with an U(1) R symmetry, consisting of a single right handed neutrino superfield with an appropriate R charge. The lepton number (L) of the standard model fermions are identified with the negative of their R-charges. As a result, a subset of leptonic R-parity violating operators can be present and are consistent with the U(1) R symmetry. This model can produce one light Dirac neutrino mass at the tree level without the need of introducing a very small neutrino Yukawa coupling. We analyze the scalar sector of this model in detail paying special attention to the mass of the lightest Higgs boson. One of the sneutrinos might acquire a substantial vacuum expectation value leading to interesting phenomenological consequences. Different sum rules involving the physical scalar masses are obtained and we show that the lightest Higgs boson mass receives a contribution proportional to the square of the neutrino Yukawa coupling f . This allows for a 125 GeV Higgs boson at the tree level for f ∼ O(1) and still having a small tree level mass for the active neutrino. In order to fit the experimental results involving neutrino masses and mixing angles we introduce a small breaking of U(1) R symmetry, in the context of anomaly mediated supersymmetry breaking. In the presence of this small R-symmetry breaking, light neutrino masses receive contributions at the one-loop level involving the R-parity violating interactions. We also identify the right handed neutrino as a warm dark matter candidate in our model. In the case of R-symmetry breaking, the large f case is characterized by a few hundred MeV lightest neutralino as an unstable lightest supersymmetric particle (LSP) and we briefly discuss the cosmological implications of such a scenario.

h → γγ in U(1) R -lepton number model with a right-handed neutrino

“…We would like to reiterate that the lepton numbers have been identified with the (negative) of Rcharges such that the lepton number of the SM fermions are the usual ones whereas the superpartners of the SM fermions carry non-standard lepton numbers. With such lepton number assignments this R-symmetric model is also lepton number conserving [91,92,95].…”

“…A sneutrino thus can play the role of a down type Higgs boson, a phenomenon which has crucial implications [79,86,91,92,95] for our purpose that we would discuss later in this work. The right handed neutrino, on the other hand, not only provides a small tree level Dirac neutrino mass but also gives rise to an additional tree level contribution to the Higgs boson mass proportional to the neutrino Yukawa coupling [95]. When the R-symmetry is broken, a small ( 0.05 eV) Majorana mass for one of the active neutrinos is generated at the tree level while the right handed sterile neutrino can have keV Majorana mass and can be accommodated as a warm dark matter candidate.…”

“…Cosmological implications of having such a light neutralino is briefly discussed in ref. [95] for this model. Some general studies regarding light neutralinos can be found in [107][108][109][110][111][112][113][114][115][116].…”

“…In this paper we consider the minimal extension of a specific U(1) R symmetric model [91,92] by introducing a right handed neutrino superfield [95]. In such a scenario the R-charges are identified with lepton numbers such that the lepton number of SM fermions and their superpartners are negative of the corresponding R-charges.…”

“…We consider a minimal extension of an R-symmetric model, first discussed in [91,92], by extending the field content with a single right handed neutrino superfield [95]. Along with the MSSM superfields,…”